This invention relates to drill guides as used in orthopaedic surgery and has specific relevance to an adjustable drill guide.
Heretofore, drill guides for use in orthopaedics include a plurality of holes for accommodating a drill bit therethrough. The drill guide may be connected to a prosthetic implant to aid the surgeon in aligning the drill bit with preformed holes in the implant. A fastening device such as a screw is inserted into the hole in the bone formed by the drill and seats within the implant. Typically, such drill guides include a body having a plurality of guide holes wherein the guide holes are fixed relative to the body. This requires that exact tolerances be maintained during manufacture of the drill guide so that a bore drilled using the guide matches a corresponding hole in the implant. If the drill guide is slightly mismatched to the implant, the bores through the bone will not exactly align with the holes in the implant.
In U.S. Pat. No. 4,865,025, a drill guide apparatus 1 is disclosed having a slider 4 that is moveable within channel 8 of branch 3b. Slider 4 includes two transverse passages 5 for receiving a drilling guide 6, which is dimensioned to receive a piercing pit 7 adaptable to a surgical drill. Slider 4 moves axially within passage 8 and is clamped into position by a locking mechanism. Although axial adjustment is possible, the apparatus requires that the holes in the bone or implant (t1 and t2) properly align with passages 5 of slider 4 upon a certain axial position of slider 4 within passage 8 and proper angular alignment of branch 3b within the bone or implant.
U.S Pat. No. 4,667,664, discloses a drill guide having a so-called target mechanism 46 for permitting alignment of the openings in the intramedullary nail. After the desired position is reached, set screw 70 is tightened for locking targeting mechanism in position. The target mechanism includes an alignment member with an axis that, through movement in four degrees of freedom, can be aligned coaxially with the blind hole. Again, however, any such adjustment is dependent upon the holes in the bone or implant properly aligning with passages within target mechanism 46.